1. Field of the Invention
This invention relates to a method of manufacturing precisely formed taggant materials or particles of uniform size and information content, preferably formed from polymeric, protein, or carbohydrate materials. Specific combinations of shape, size, color, reflectivity, refractive index, surface geometry, imprinting, optical effect, and electromagnetic properties can be used to uniquely tag manufactured articles.
Taggant materials or particles can be mixed into bulk products (foods, explosives, pharmaceuticals, paper, polymers), applied to the surface of articles, or incorporated into inks, paints, or coatings.
A relatively small amount of optically or electronically readable information can be carried by the taggant materials and larger amounts of information can be distributed among a multiplicity of taggant materials.
2. Description of Related Art
Low viscosity polymer materials can be precisely formed by casting or molding against a master tool bearing a microstructured pattern. Under suitable process conditions the polymer article thus formed will retain an accurate impression of the microstructure pattern of the mold. Cast or molded polymeric articles are commonly manufactured at large scale, with dimensions ranging from millimeters to meters.
In contrast, the dimensions of the subject invention are in the micrometer range, typically between one micron and 500 microns in their largest dimension. An exemplary taggant material or particle of the present invention might be roughly fifty microns in diameter and ten microns thick.